Hello @JackWy
It will work, but may introduce some performance issues due to bridging all of the traffic from unit #4 through unit #2 in software on the limited CPU in that unit.
What I would do instead is pick up another inexpensive, unmanaged Ethernet switch – something small like a 4-port or 5-port unit. Place it near Nest WiFi Pro unit #2 and connect it back to the core switch using the Ethernet line currently connected to WiFi unit #2. Now, you can connect unit #2 to that switch using a short cable, and connect WiFi unit #4 to that new switch as well.
Basically, we're building a trunk and branch wired network of switches and hanging all of the secondary/point Nest WiFi units off of that network.
You can (and should) also connect as much of your other equipment to this network as you can. Fixed devices like computers (including laptops that spend most or all of their time in one spot), streaming video/TV devices, and (especially) gaming consoles will benefit significantly from being wired, leaving maximum WiFi capacity for all of the remaining devices that can't be wired.
